You have a phenol red lactose Durham tube and a phenol red sucrose Durham tube, both yellow, with a gas bubble in the lactose tube but no bubble in the sucrose tube. Bacterium A can ferment both lactose and sucrose while producing gas in both. Bacterium B can use both sugars also but only produces gas when fermenting lactose. Which bacterium did you inoculate into both Durham tubes?
a) Bacterium A
b) Bacterium B
c) Cannot be determined
d) Both A and B